FIG. 5 is a side view showing a structure of a running gear equipped with a link.
A track-type work machine is equipped with a pair of running gears 10, shown in FIG. 5, at the right and left sides of the lower part thereof. The running gear 10 has a crawler belt 1. The crawler belt 1 is constructed such that a plurality of links 3 are circularly interlinked by connecting pins 4, in which a shoe plate 2 is fixed to each of the links 3 by a bolt.
The running gear 10 is provided with a track frame 5 disposed in the longitudinal direction of the work machine, and an idler tumbler 6 and a sprocket wheel 7 which are rotatably mounted to the front and the back of the track frame 5, respectively. In addition, three pair of roller devices 9a, each having a pair of front and back track rollers 8, and a roller device 9b, having a track roller 8, are mounted to the lower part of the track frame 5 between the idler tumbler 6 and the sprocket wheel 7, wherein each roller 8 is swingable in a vertical direction and rotatably supported to the track frame 5. Each roller 8 of the track roller devices 9a and 9b rolls in contact with a wear rail of the link of the crawler belt (referring to a patent literature 1).
FIG. 6 is a partially exploded perspective view showing the crawler belt of FIG. 5.
The crawler belt 1 is composed of the shoe plate 2, the link 3, a bushing 11, the connecting pin 4 and a dust seal 12. Each element is coupled to each other, as shown in FIG. 6, such that the bushing 11 is tightly forced into the link 3 and then the connecting pin 4 is slackly fitted into the bushing 11. Then, the connecting pin 4 is tightly forced into another link 3b arranged at the outside of the former link 3 and coupled thereto. The crawler belt 1 bends between the bushing 11 and the pin 4 (referring to a nonpatent literature 1).
FIG. 7A is a plane view showing the wear rail of the link of FIG. 6, and FIG. 7B is a side view showing the link provided with the wear rail shown in FIG. 7A.
The link 3 is formed with the wear rail 13 which supports the weight of the machine at the upper surface and also rolls in contact with the track roller (represented by reference number 8 in FIG. 5), as shown in FIG. 7B. In addition, the idler tumbler treads on the wear rail 13. Further, the link 3 is formed with a shoe-mounting surface 14, to which the shoe plate 2 is mounted, at the opposite side of the wear rail 13. Furthermore, the link 3 is formed with a bushing-forcing bore (a link connecting bore) 15, in which the bushing 11 is forced, at one end thereof, and with a pin-insertion bore (a link connecting bore) 16, in which the pin 4 is fitted, and a seal counter bore (not shown), in which the dust seal 12 is fitted, at the other end thereof, wherein the pin-insertion bore 16 and the seal counter bore are concentricity aligned. In addition, the link 3 is formed with a bolt-insertion bore (not shown), in which a bolt is fitted for mounting the shoe plate 2, and with seats 17, each on which a nut for mounting the shoe plate 2 is seated. A window 18 is a space for seating the nut (referring to a patent literature 2).    Patent literature 1: Japanese Patent Publication No. 2002-362441 (paragraphs 22 to 27, FIG. 1)    Patent literature 2: Japanese Patent Publication No. 2004-17782 (paragraph 15, FIG. 2)    Nonpatent literature 1: “Practical machine series bulldozer” Tomoyosi Morita, Sangyou Tosho Syuppann, (1969), p 70.